Stress and periodontal disease: the mechanism
There are several studies which show that major negative life events more dependably occur in close proximity to the onset or exacerbation of illness, and the relationship between important negative life events and disease was mediated by the immune system. Research has also shown that emotional stress can modulate the immune system through the neural and endocrine systems in at least three different ways:5
- Through the autonomic nervous system pathways
- Through the release of neuropeptides
- Through the release of hypothalamic and pituitary hormones.
Stress and the immune system
Stress activates the hypothalamic-pituitary-adrenal axis resulting in the secretion of corticotropin-releasing hormone and vasopressin by the hypothalamus. This acts on the pituitary gland, which in response, secretes the pituitary corticotropic hormones to act on the adrenal cortex and increase the production and release of cortisol and glucocorticoid hormones. They are essential for a long-term stress response. Glucocorticoids modify the behaviour of lymphocytes, macrophages, and monocytes by inducing a decrease in immunocompetence. Overtime they contribute to the risk of cardiovascular disease, diabetes mellitus, rheumatoid arthritis, and other diseases.6
This decrease in immunocompetence occurs because of the following: 6
- Changes to the inflammatory response;
- Inhibition of IgA, IgG, and neutrophil function that leads to an increase in bacterial colonization of the biofilm and a decrease in the ability to prevent connective tissue invasion;
- Changes to the initial cytokine profile in place of interleukin-1 and TNF α;
- Elevated blood glucose levels;
- A change in the rates of certain growth factors.
A prolonged period of chronic cortisol elevation and the immune dysfunction leads to the deregulation of the inflammatory inhibitory abilities, thereby promoting chronic inflammatory damage within the periodontium. 6